The biggest problem with the scales (or any bioelectric impedence measure, incuding the Omron) is that your hydration status can really change the readings. It's based on the speed in which a small electric current travels through your body - and water conducts at a different speed than fat. So, if you always measure first thing in the morning without having a drink first, you'll probably get consistent RELATIVE values. But I wouldn't hold that number up as an absolute body fat %.
For fun one day, try using the body fat scale when you're really dehydrated, then drink a bunch of water and get back on - you can change your BF% in less than an hour!
